1. Field of the Invention
The present invention refers to duct fans of the type having a radial impeller, and more specifically to a housing for such duct fans, which housing is easy to assemble and, which, merely through the assembly, firmly secures the motor bridge to the fan motor mounted thereon, as well as its radial impeller in its proper place within the housing.
2. Description of the Prior Art
Duct fans are extensively used, e.g. in ventilation and air-conditioning systems in homes, offices and industrial plants, as well as in evacuation systems for toilets, shower rooms and other wet or damp spaces. In connection herewith, duct fans are easy to install in appropriate places within the various ducts, a fact contributing to the relatively extensive use of such fans. In connection herewith, the cost, however, is a limiting factor. It is thus desirable to produce these duct fans with a maximum efficiency in order to achieve a minimum cost without, however, having to lower the standards of quality or function.
A duct fan housing comprises two substantially funnel- or bell-shaped components, one of the components having an air inlet and the other one of the components having an air outlet. The inlet and the outlet are provided in the form of connecting sleeves adapted to connecting standard ventilating ducts. The two components are designed such that one of them fits onto the other across a distance at the wider ends of the components, and screws or rivets are inserted through the overlapping portions to keep the components together. Prior to the assembly, the motor and its accompanying fan generator are placed in one of the components and secured therein by means of a motor bridge extending diagonally across the components and being secured in place through a screw or rivet joint.
Today, once the components have been fitted to one another, manual work is required to secure the components together through a screw or rivet joint or the like. Manual labor is however so expensive, that efforts are made in every possible way to reduce the need therefor. Drilling and screw or rivet joining may be carried out by robots, but when keeping in mind that the remaining assembly work also hitherto had to be executed manually, the use of robots exclusively for the assembly operation was never economical.